1. Technical Field
The present invention relates to robotic arms and more particularly to a method of path planning for array-based pick-and-place performed with a robotic arm and a compensator for use with the method.
2. Description of Related Art
An array-based pick-and-place process performed with a robotic arm is accompanied by the accumulation of errors; as a result, the robotic arm can only operate within a limited range of duty. Regarding related prior art, WO 2009/007824 A1 discloses effectuating X-Y plane compensation with a linear guideway and a parallel four-bar linkage and using a spring sensor to feed back an overtravel-related alert signal whereby a robotic arm stops its operation. However, the spring sensor of WO 2009/007824 A1 cannot sense the distance traveled by the robotic arm in the X-Y direction. Furthermore, the alert signal sent from the spring sensor causes the robotic arm to stop operating and thus fail to perform the rest of the array-based pick-and-place process.
U.S. Pat. No. 4,745,681 discloses sensing, with force sensors disposed in the vicinity of a gripper, the pressure of a gas drawn in or discharged through a pin hole, moving the gripper repeatedly to enable a pin to align with the pin hole as well as possible if the gas pressure is sensed to be unevenly distributed, and inserting the pin into the pin hole with the gripper as soon as the force sensors sense that the gas pressure is uniformly distributed. However, the invention claimed by U.S. Pat. No. 4,745,681 has drawbacks as follows: taking much time to wait for the equilibrium of gas pressure level; incurring too much costs because one gripper requires four force sensors; and being inapplicable to high-precision products.